Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C1/00—Refining of pig-iron; Cast iron
  • C21C1/02—Dephosphorising or desulfurising
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C1/00—Refining of pig-iron; Cast iron
  • C21C1/08—Manufacture of cast-iron

Definitions

• the invention relates to a process for treating a lamellar graphite cast iron intended for the manufacture of camshafts according to which the said cast iron is brought to the melting temperature before extracting the oxides from the cast iron after settling.
• the invention relates more particularly to the process for treating such a lamellar graphite cast iron in order to prepare the camshafts for a surface reflow treatment.
• the publication FR-A-2 292 043 describes a process for adding 15 to 50% by weight of magnesium particles to the molten metal preceding the casting operation.
• the addition of such an amount of magnesium in a cast iron with lamellar graphite makes it possible to deoxidize the cast iron but transforms the lamellar graphite into nodular or spheroidal graphite.
• the subject of the invention is the production of camshafts of cast iron with lamellar graphite, the machining of which is easier than the machining carried out on camshafts of cast iron with nodular or spheroidal graphite.
• the subject of the invention is also the production of camshafts of cast iron with lamellar graphite capable of undergoing a surface reflow treatment giving said camshafts a much greater hardness, without causing the creation of defects in particular in the structure of the parts. finished.
• the object of the invention is therefore to deoxidize the lamellar graphite cast iron before it is cast, without modifying the lamellar structure of the graphite, with the aim of eliminating the defects generated during the surface reflow treatment.
• the deoxidizing element when the cast iron has a high sulfur content, the deoxidizing element, introduced in small quantities, reacts only with the sulfur.
• the object of the invention is therefore to provide an addition of a deoxidizing element in a very low sulfur cast iron.
• the process is characterized by the fact that 0.001% to 0.02% by weight of a deoxidizing element is introduced before casting into the iron bath in order to obtain a low-lamellar graphite cast iron. oxygen and nitrogen content.
• the process consists of a first step of melting the lamellar graphite cast iron which is brought to a melting temperature of around 1500 ° C.
• the metal bath obtained after melting undergoes desulfurization.
• This desulphurization can be carried out, for example, by adding a desulphurizing agent introduced inside a fusible conduit with bubbling of an inert gas, the temperature being maintained around 1420 ° C, so as to obtain at the end of this treatment a sulfur content of less than 0.035% by weight.
• the process continues with decantation lasting twenty minutes, which allows the oxides present in the cast iron to be extracted in the form of precipitates, such as MgO, MgS, etc.
• This deoxidation does not reach dissolved gases, such as oxygen or nitrogen dioxide.
• the decantation carried out is followed by a temperature rise which allows the addition of a deoxidizing element consisting of magnesium in the form of an alloy containing from 5 to 30% by weight of magnesium.
• the deoxidizing element consists of cerium.
• the deoxidizing element consists of barium.
• the deoxidizing element consists of calcium.
• the addition of magnesium is carried out for example by using a fusible conduit.
• the magnesium thus introduced forms complexes with the oxides remaining in the cast iron, which are inert during a surface reflow treatment.
• Camshafts whose area occupied by faults is less than 1% of the area of the camshaft are considered to be "acceptable” defects. without adding Mg addition of Mg + desulfurization addition of Mg (S ⁇ 0.035%) % of parts without defects 10 69 75 % of "acceptable" parts 40 28 25 % of discarded parts 50 3 0

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Heat Treatment Of Articles (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=9445147

Family Applications (1)

Country Status (3)

Cited By (5)

Citations (4)

• 1993
  • 1993-03-19 FR FR9303182A patent/FR2702687B1/fr not_active Expired - Lifetime
• 1994
  • 1994-03-15 DE DE1994618516 patent/DE69418516T2/de not_active Expired - Fee Related
  • 1994-03-15 EP EP19940400552 patent/EP0616040B1/de not_active Expired - Lifetime

Patent Citations (4)

Non-Patent Citations (2)

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